Fix stale dev types causing build failure after route deletion (#86489)
When running `next dev`, then stopping it, deleting a route, and running
`next build`, the build would fail with a type error like:
```
.next/dev/types/validator.ts:78:39
Type error: Cannot find module '../../../app/simple-test/page.js'
```
The root cause here is a fundamental tension: we have **one
tsconfig.json** that needs to serve **two different modes**. When
`isolatedDevBuild` is enabled (which is the default), Next.js outputs
types to different directories:
- Development: `.next/dev/types/`
- Production: `.next/types/`
To avoid tsconfig.json changing every time you switch between dev and
build (which causes git noise and forces IDE reloads), we proactively
include both paths:
```json
{
"include": [
".next/types/**/*.ts",
".next/dev/types/**/*.ts"
]
}
```
The problem is that TypeScript checks ALL files matching these patterns.
If `.next/dev/types/validator.ts` exists from a previous dev session and
contains imports to routes that have since been deleted, TypeScript
fails during build because those imports point to non-existent files.
You might ask: why not just completely separate them with two tsconfigs?
The issue is that would require users to know which tsconfig to use for
their IDE, and switching between configs manually defeats the purpose of
a seamless dev/build experience. The single tsconfig approach is
intentional.
The fix filters out `.next/dev/types` files programmatically when
running type check during build, without touching tsconfig.json:
```typescript
let fileNames = effectiveConfiguration.fileNames
if (excludeDevTypes) {
const devTypesPattern = /[/\\]\.next[/\\]dev[/\\]types[/\\]/
fileNames = fileNames.filter((fileName) => !devTypesPattern.test(fileName))
}
```
This way the tsconfig stays unchanged (no git churn, IDE stays happy),
dev types are preserved for concurrent dev sessions, and build only
type-checks its own `.next/types` directory.
next.js
52ea3cba - Fix stale dev types causing build failure after route deletion (#86489)
